The characteristics of the peripheral vasculature are important in determining arterial pressure and left ventricular performance in patients with congestive heart failure (CHF) and hypertension. Peripheral vascular resistance is the parameter most frequently used to describe the peripheral vascular bed. However, recent studies suggest that frequency-dependent vascular impedance may be a more sensitive indicator of disease and therapeutic response. The determination of this impedance requires Fourier analysis of simultaneously recorded pressure and blood flow waveforms. Heretofore, pressure and waveforms have typically been measured at the ascending aorta, requiring significant system invasion, and thus limiting the usefulness of the procedure as a diagnostic and monitoring tool.
An alternative impedance measurement technique uses the peripheral arterial pressure pulse contour and a measure of cardiac output to derive vascular impedance properties. This method is minimally invasive, requiring only a brachial artery puncture to obtain the peripheral pressure signal, and thus offers the potential of practical clinical use. Proximal compliance, distal compliance, inertance and peripheral resistance are all determinable from the pressure pulse contour and cardiac output. As set forth below, the present invention utilizes the alternative impedance measuring technique to diagnose and monitor the vascular abnormalities and characteristics of hypertension and CHF.